1. Field of the Invention
The present invention relates to a recording apparatus that records a digital stream onto a recording medium such and relates to a playback apparatus and a recording medium.
2. Description of the Related Art
In the commercialization of the above recording apparatus, maintaining compatibility with digital streams recorded on recording mediums is the important responsibility for makers of such recording apparatuses. To ensure the compatibility, each maker has been actively engaged in standardization of recording formats employed for the recording mediums. As their achievements, various unified standards including the DVD-Video recording standard have been established.
While the makers keep step with one another, each maker tries to differentiate their products from other makers' products. In such efforts, each maker tends to commercialize recording apparatuses featuring “extended control”. The “extended control” featured by recording apparatuses is playback control whose contents can be freely determined by the maker of the recording apparatuses. A format defined by the DVD-Video recording standard or the like has universal values, and so does not allow any makers to define contents of playback control that do not comply with the format. On the other hand, universal values are not required for extended control, and therefore, makers can define commercially strategic contents, fashionable contents, and the like, as the contents of extended control unique to the makers.
With the widespread use of multi-user compatible optical discs, however, extended control alone may not truly satisfy users although differentiation of the products from others can be achieved by the extended control. A multi-user compatible optical disc is an optical disc shared by a plurality of users. An optical disc with a large capacity of 40 gigabytes or more is often designed as multi-user compatible. For such a multi-user compatible optical disc, it is not desirable to provide uniform playback control for all the users. In the present era of individuality, preference and convenience for each individual user should be highly respected. For playback of a multi-user compatible optical disc, too, such extended control that can satisfy preference and convenience for each individual user is highly desirable. However, providing individual extended control for each of a plurality of users sharing one recording medium inevitably complicates the data format of the recording medium and the processing of the apparatus side. The larger the number of users, the more they become complicated, thereby placing huge burdens on the makers.